by Alan M. Dershowitz , Gatestone Institute, July 26, 2018

Pictured: Michael Cohen, (left) former personal lawyer for President Donald Trump, exits the United States District Court in New York on May 30, 2018. (Photo by Eduardo Munoz Alvarez/Getty Images)

Someone leaked the lawyer/client confidential tape containing a conversation between President Donald J. Trump and his lawyer Michael Cohen. A former judge, assigned by the presiding judge to evaluate the seized tapes, reportedly concluded that this conversation was privileged. Yet someone leaked their contents. The President Trump's current lawyer, Rudy Giuliani, then waived the privilege as to that tape. He said he never would have waived it had its existence and content not been improperly leaked.

So, the question remains: Who leaked this privileged material? If it was anyone in the Trump camp, there would be no violation of confidentiality, as the privilege belongs to the client, namely Trump, who can waive it. But no one else, most especially his lawyer, may properly waive the privilege. And Giuliani has categorically denied that it was leaked by Trump or anyone on his behalf. Indeed, he has expressed outrage at the leak.

Whom does that leave? Cohen is an obvious suspect, although I am confident that his excellent and experienced lawyer, Lanny Davis, would not have done so. Perhaps Cohen himself, who ran into Michael Avenatti at a restaurant, told him about the tape. We simply do not know.

It is unlikely that any judicial or prosecutorial authority is responsible for the leak, because they would have more to lose than to gain if they were caught.

The reason this is important to all Americans, beyond the immediate parties to this taped conversation, is that it may well discourage clients, patients, penitents and others from confiding in their lawyers, doctors, priests and the professionals who promise them confidentiality. Cohen promised confidentiality and yet the world heard what his client confided in him. We know he recorded the confidential conversation without the knowledge of his client. That is bad enough. Then it was deliberately leaked by someone who must have believed he or she would reap some benefit or advantage from having the public hear it.

We must find out who is the source of this damaging leak — damaging to all Americans who place their faith in the promise of confidentiality from the professionals in whom they confide.

It is an ethical violation, subject to serious sanctions including disbarment, for a lawyer to disclose, or cause to be disclosed, privileged conversations. And for good reason. The obligation of a lawyer not to disclose confidential information is codified in Rule 1.6 of the New York Bar. This broad rule prohibits, subject to exceptions not present in this case, any knowing disclosure of confidential information. That plainly covers the kind of conversation we have all now heard in the leaked tape: namely, the discussion between Trump and his attorney as to how to deal with a potential messy problem. We may not like the subject matter under discussion, but it is fully covered by the privilege, as the former Judge rightly found. That is why this leak is so difficult to fathom. The risks to the leaker are greater than any short-term benefit. But the fact remains that the leak occurred, and now it is imperative that the leaker be exposed and held to account.

This can be accomplished in several ways. Judge Kimba Wood, who is presiding over the matter, could hold a hearing in which the potential suspects are is placed under oath and asked the simple question whether they leaked the contents of the tape and/or whether they know who the leaker was. Obviously, people who are willing improperly to leak confidential material may also be willing to lie about it under oath, but the consequences of lying under oath are greater than leaking, as leaking is not a crime but perjury is.

Notwithstanding the importance of this issue, there seems to be little interest among the participants in determining who leaked the tape. There has been no call for an investigation. Perhaps this is because both sides think they benefited from the leak. I leave that to the public, and eventually the courts, to determine. What is clear is who was hurt by the leak: all Americans who rely on confidentiality – which means all of us – were hurt when the world was allowed to listen to a lawyer/client privileged conversation, that no one except the participants should ever have heard.

Alan M. Dershowitz is the Felix Frankfurter Professor of Law Emeritus at Harvard Law School and author of "The Case Against Impeaching Trump", Skyhorse Publishing, 2018.